## Description This PR introduces support for `formSheet` presentation on Android andbrings support for custom detents on iOS.I've ensured that this PR is backward compatible, i. g. I've broughtback support for `medium`, `large` and `all` options, which weresupposed to be dropped.Please note this this changes will work with react-native-screens 4.0.0onwards.There is plan to land this feature on v6 line (will requirereact-native-screens 3.35.0 or 3.36.0 or newer), however it is deferredfor now.Associated PR:*#11516## DisclaimersThe extended functionalities of `formSheet` stack presentation do comewith its limitations.* Android supports only up to three possible detent values. * `fitToContents` detent level can not be yet passed together with othervalues (this is work in progress and if sensible API is feasible we'llrelease it later).* there are limitations on flex layout inside the sheet's content oniOS. To mitigate other, more staggering issues, we do not notify React'slayout system on sheet height's changes. This causes e.g. to causeissues when trying to center elements vertically depending on currentsheet height. If that's your use case - form sheet is not eligible yet.If you happen to notice any issue related to the formsheet API considerforwarding it to the [`react-native-screens`repository](https://github.com/software-mansion/react-native-screens).Thanks!**Test plan**Since this change involves native-stack solely I've tested this onExample & FabricExample apps in [`react-native-screens`repository](https://github.com/software-mansion/react-native-screens/tree/main/Example)(e.g. `Test1649` can be used).---------Co-authored-by: Satyajit Sahoo <satyajit.happy@gmail.com>